1. Field of the Invention
The subject invention relates to grout floats and more particularly to constructions for grout floats. Still more particularly, it is concerned with methods and means for mounting a handle to a grout float blade whereby the handle or the entire float can be overmolded with a resilient layer of elastomeric material.
2. Prior Art
Grout floats are used in the spreading and removal of excess water from grout prior to the application of tiles to walls, floors and other surfaces. Grout floats are well known in the art and generally take the form of a flat rectangular blade member of metal, plastic or composite material with a handle mounted to its upper surface. The smooth bottom of the tool may be the exposed underside of the blade, a layer of suitable material applied or affixed to the blade, or a laminate formed, for example, of resilient layers of plastic, composite, rubber, sponge, or other well known materials, bonded to the blade.
The early prior art grout float handles were of wood or other convenient material. Cantilevered on a single metal shank, or provided with metal mounting flanges at their ends, these handles were conventionally mounted to the float blade by welding or riveting. Typically, the blades of these tools were susceptible to bending under downward or lateral force. Repeated flexing quickly led to fracturing of the weld or loosening of the rivets and eventual separation of the handle from the blade. Employing heavy construction to minimize or eliminate the problem of flexion increased the weight and production cost of the tool.
Additionally, tools made of exposed metal or employing unprotected metal mounting components were especially susceptible to wear and resulting damage through abrasion or corrosion. Attempts were made to reduce the float""s exposure or susceptibility to wear and deterioration by employing assemblies with interlocking components. Few of these were successful, and those generally required multi-step manufacturing operations that proved to be prohibitively expensive.
Present grout floats often use injection moldable plastics, such as glass-filled nylons or polyolefins for the handle. However, when hollow molded plastic handles are used, watertight seals must be maintained around the joints in the component plastic parts. In use, the tool is repeatedly subjected to immersion in highly abrasive slurries and submerged in water for cleaning. If liquid leaks into the handle""s hollow cavities, the life of the tool and the weight advantage of a hollow structure are reduced significantly. To achieve the tolerances necessary for proper handle assembly with watertight seals, the manufacturing processes become complex and expensive.
Fabricated handles incorporating combinations of the foregoing constructions for hand tools are well known. Typically, U.S. Pat. No. 5,615,445 by C. Kelsay and A. Ness shows a handle assembly having a protruding ridge on one section that is received by a recessed grove on the opposite section. This groove and ridge combination improves the fit between the two core sections and promotes a watertight seal. The ""445 patent illustrates the use of posts and tubes for guiding the member sections into proper alignment; however, it relies on means, such as screws to lock the handle sections together. When these become loose through normal use, the integrity of the entire assembly is compromised.
With extended use, handles of wood, metal, or rigid synthetic materials tend to become uncomfortable to the user""s hand, arm and shoulder. Over time, contact of the skin with the grout-covered unyielding handle surface causes painful abrasions, blisters, and eventually, open wounds. It is now common practice to provide tool handles with a soft outer layer for comfort and protection. Typically, the tool handle is formed with a hard core made up of one or more components. In manufacture, the core is rigidly attached to the blade and then placed in a mold and overmolded with a resilient coating, usually of a thermoplastic elastomer. In some instances, both the handle core and the blade are overmolded so as to provide the tool with a unitary resilient outer layer.
Such handle cores can be attached to their blades by a variety of methods. In the 4,724,572 patent, by way of example, the blade is provided with an opening in which the handle is retained by tangs. This requires a special cooperative structure between the handle and blade with material and shaping limitations and the prospect of ultimate loosening resulting from wear and bending of the tangs. In most cases, once the core elements begin to separate or the handle and blade become loose, the overmolding prevents the tool from being repaired.
No known prior art grout float provides a method and cooperative means for both forming a handle core suitable for overmolding and securing the handle to the blade, much less for doing so in a single action. The subject invention serves all of those functions.
As will be demonstrated, the novel construction of the invention allows the handle core and blade components to be assembled and permanently securely joined in a single motion without the use of welds, rivets, screws or adhesives. The ease of the process and the elimination of need for any additional labor, tools or hardware to complete the assembly of the handle core and the blade provide clear advantages over prior grout float constructions.
The present invention affords significant practical advantages and ergonomic improvements over the art by providing a lightweight handle core rigidly mounted to a blade that can be fully or partially overmolded for the user""s comfort and to prevent the penetration of water into the core interior.
It is an object of the invention to provide a construction whereby the two component core sections defining the handle core are securely locked together and the core is permanently rigidly attached to the blade in a single self-locking motion. The locking of the handle core sections is achieved by means of interlocking detents, preferably mating pairs of bosses and receptacles, associated with the handle core sections. Securing of the handle core to the blade is accomplished by the interaction of connectors, preferably a pair of tongues formed on the handle core sections, and one or more retainers, preferably one or more flanges, formed on the blade.
In its preferred form, the grout float assembly includes a blade having an upper surface. An upstanding flange is provided on the upper surface. The flange has an opening adapted for receiving and frictionally interlocking with a pair of tongues. The handle core is made in two sections that are adapted to be assembled into a single unit. The ends of the unit are configured to abut and conform closely with the upper surface of the blade.
The core sections are provided with confronting, interlocking bosses and receptacles. The bosses and receptacles are axially aligned and tapered. Cooperating detents such as annular rings on the bosses and annular grooves in the receptacles interlock securely when the bosses and receptacles are mutually engaged and the handle core sections are forced together. The core sections also have confronting tongues positioned to pass through and frictionally engage the opening in the blade flange and thereby secure the handle to the blade when the boss and receptacle are interlocked.
The tapered tongues produce a wedging action when inserted through the flange openings whereby the locking union of the complete assembly is enhanced and strengthened. The wedging action includes two wedging forces. The first of these is produced when the tapered tongue on each core section slides frictionally against the upper and lower edge of the flange opening. The effect of this action is to draw the ends of the handle core into close, rigid contact with the upper surface of the blade. The second results when the tapered faces of the opposing tongues frictionally engaged each other as the core sections are brought into their final interlocked position. During the assembly motion, the tapered tongues and flange openings position assist the bosses and receptacles in positioning and guiding the core sections and blade into proper alignment.
In lieu of the aforementioned annular rings and grooves, a strong and secure attachment between the component sections of the handle core can be achieved by providing alternative interactive detents on the respective core components. Among various configurations, these can be in the form of cooperating axial vanes and grooves formed on bosses and receptacles associated with the core sections (not shown). Alternatively, the detents can be cooperatively positioned raised and depressed features formed on the core sections for interengagement when the sections are joined. Advantageously, the natural resilience of the plastic material chosen for the handle core sections allows various detent structures to be used. The tapers and drafts can readily be adapted to allow the interlocking bosses, receptacles, tongues and flange options to receive and retain one another. If desired, short locator pins can be provided to assist further in guiding the core sections"" tongues and flanges into proper alignment.
It is another object of the invention to overcome the weight disadvantages and other deficiencies of the prior grout floats that make use of solid plastics, metal, wood or other handle materials or which make use of hollow materials with expensive or ineffective component part seals.
As previously mentioned, the construction of the subject invention is especially suited to the application of a resilient overmolded covering to the handle alone or to the entire tool. In one preferred embodiment, the handle core sections forming the ergonomically shaped handle core are molded from a hard, durable plastic material that provides strength and rigidity to the tool once the handle core is secured to the blade. The outer layer overlying the handle core is molded from a relatively soft, resilient material that provides a comfortable, durable, attractive grip. To enhance the effectiveness of the overmolding process, channels are provided adjacent the ends of the handle core to allow the overmolded material to flow into the hollow handle core thereby forming a fluid-tight seal between the periphery of the handle core and the upper surface of the blade and enclosing and further securing the connection between the tongues on the handle core sections and the flanges on the blade.
A specific object of the present invention is to provide an apparatus of the above described characteristics and advantages wherein once assembled the handle core and blade perform as a rigid unitary piece. A further object is to provide a method and means for producing a unitary assembly of the type described which lends itself to overmolding with a resilient material for comfort, durability, and attractive appearance.